Prima facie, CBI officials believe, it is impossible for on outsider to get hold of such information without the help of an insider, the people said.

The CBI, in a statement on September 21, said the petitioner was “in possession of information from highly confidential internal documents, which is a serious offence”.

The Central Bureau of Investigation is looking into an alleged leak of information from “highly confidential internal documents” pertaining the IRCTC hotel scandal, where former railways minister Lalu Prasad is a key accused.

The agency is examining any possible insider involvement, after a petitioner who last month moved the Supreme Court in the case was found to be in possession of some “classified” information, people with direct knowledge of the matter said.

The petitioner, a resident of Bihar, had sought action against CBI director Alok Verma, alleging that he had interfered in the investigation of the IRCTC scandal. He accused the director of “stopping for more than an hour” CBI sleuths who were to carry out a raid on the accused in the case. Rashtriya Janata Dal supremo Lalu Prasad, his wife Rabri Devi and son Tejashwi Yadav stand charge-sheeted in the scandal.

The CBI, in a statement on September 21, said the petitioner was “in possession of information from highly confidential internal documents, which is a serious offence”.

Prima facie, CBI officials believe, it is impossible for on outsider to get hold of such information without the help of an insider, the people said. The CBI statement was issued in response to a complaint given by CBI special director Rakesh Asthana to the government.

As first reported by ET, Asthana alleged that Verma had tried to stall the raids on Lalu Prasad. Asthana’s complaint was referred to the Central Vigilance Commission by the government. A factfinding inquiry is being held by the commissioninto the allegations